Subsoil plow and shank



P 1964 D. L. SHELTON SUBSOIL PLOW AND smmx Filed Decl .11, 1962 0 01' AN L- SHELTON United States Patent 3,148,738 SUBSOE PLOW AND SHANK Dothan L. Shelton, 540 Amarillo Bldg, Amarillo, Tex. Filed Dec. 11, E62, Ser. No. 243,938 4 Claims. (Cl. 172-699) This invention pertains to subsoil cultivation and more particularly to a deep furrowing plow with a spring or vibrating shank.

This invention provides for an improved shank and plow for subsoil apparatus as are disclosed in my US. Patent No. 2,699,715 entitled Earth Furrowing Apparatus.

With subsoilers it is desirable to have a certain amount of flexibility in the line of draft so that a vibrating action is achieved. However, it is not desirable to have appreciable lateral movement, i.e. horizontal movement normal to the line of draft. This lateral movement will result from a lateral bending of the horizontal portion of the shank, or from a twisting or torsional displacement, or from a combination of these two displacements. A broad, thin strap has good characteristics; however, the portion beneath the soil level should be narrow.

An object of this invention is to provide a deep furrowing shank which has the necessary lateral rigidity while maintaining a high degree of flexibility along the line of draft.

Another object of this invention is to provide such a shank in which the underground portion is narrow in the line of draft.

Another object of this invention is to provide a device as above in combination with a plow so that the plow itself will be self-sharpening.

A further object of this invention is to provide such a combination which requires a minimum amount of power to operate.

Still further objects are to achieve the above with a device that is sturdy, compact, durable, simple, and reliable, yet inexpensive and easy to manufacture.

The specific nature of the invention as well as other objects, uses, and advantages thereof will clearly appear from the following description and from the accompanying drawing, in which:

FIG. 1 is a perspective view of one embodiment of this invention.

FIG. 2 is a perspective view of a second embodiment of this invention.

FIG. 3 is an elevational view of the shank of the first embodiment with the plow attached.

FIG. 4 is a sectional view of the first embodiment as taken on line 4-4 of FIG. 5 or FIG. 6.

FIG. 5 is a cross sectional view as taken on line 55 of FIG. 4.

FIG. 6 is a view of the plow as taken on line 66 of FIG. 3.

FIG. 7 is an elevational view showing the position of the plow on the bottom of the furrow and the angle of wear.

One embodiment of this invention, as seen in FIG. 1, is made from a rectangular strap of spring steel.

Although the dimensions may be varied for different applications, it will be described as a strap of steel two inches wide and one inch thick. Near one end there is a single bolt hole 10 for attaching the shank to the frame of a plow device as disclosed in my Patent No. 2,699,715 mentioned above. The hole extends through the broad side of the strap so that the strap is mounted in a flat position and has considerable width; therefore high resistance to the lateral shifting. With less thickness, the shank has less resistance to vertical shifting or bending or flexing as might occur due to resistance on the earth working element.

This configuration continues over a horizontal stretch 3,148,738 Patented Sept. 15, 1964 12 which is some fifteen inches in length. Shortly to the rear of bolt hole 10 the shank 12 is split along a vertical plane parallel to the line of draft, as may clearly be seen in the drawings. At the beginning of this split there is a circular vertical bore 14 to eliminate a high stress point as would otherwise occur from the flexing action of the shank. Bar 16, one of the split elements, which will be a one inch by one inch bar of metal, is bent downward along an eleven inch radius. The rearward downward portion or section is tangent to the horizontal portion or section, i.e. it flares smoothly into it. The second element extends back and has upward loop or coil 18 therein. As shown in the drawings, the loop 18 is a single turn of a helix and is turned toward bar 16 in a horizontal plane. Therefore, the second element 20 will be in line with element 16. By in line is meant in the line of draft which is parallel to section or portion 12. On the extreme lower portion of element 16 and 20 are holes 22 for the passage of bolts 24.

As may be seen, the bolts 24 serve a dual purpose. First they hold earth working element or plow 26 onto the lower portion of the shank elements. Furthermore, they hold the two shank elements rigidly together at this point. Normally the elements 16 and 29 are free to move relatively to each other. This movement retains the in line flexibility or springiness of the shaft in this area. In other words, the lower or curved portion of the shank has approximately the same flexibility as though it were two inches wide and one inch thick rather than actually presenting a face to working surface of one inch and being two inches thick. This is because the two parts are free to flex one upon the other. To aid in preventing relative movement in the extreme lower end it may be desirable to place a square boss 28 upon the end of element 16, which fits a correlative depression in the lower surface of element 20. The boss is held into the depression by the bolts 24. Therefore, the shear strength of the bolts is not the sole means for holding the two elements in a fixed relationship.

The embodiment shown in FIG. 2 is similar to the embodiment shown in FIG. 1. It also has lower elements 16' and 20 which are in the line of draft. Element 16' has holes 22 at the lower portion for reception of the bolts. Likewise there is the upward turned loop 18' upon the rear element 20'. However, the two shanks 12 extend all the way forward. Instead of a single bolt hole extending vertically in the front part of the shank, there is a semi-cylindrical cavity 11 in each of the elements. Additionally there is a horizontal transverse bore 15 extending through the elements to hold them together by means of a bolt at this point. The rear element 20' terminates along the lower are at a point above the bolt holes 22' in element 16'. Therefore, the bottom of the element 20' is not attached to the bottom of the element 16' but merely rides behind like a leaf spring. As the two elements are not attached (somewhat in a cantilever fashion) there is a greater degree of flexibility. However, examination of the horizontal portion of the shank 12 will reveal that as the two elements are split all the way through that they are merely attached somewhat in cantilever fashion at the front. This means that they also have more lateral flexibility than the embodiment shown in FIG. 1.

As may be seen, the plow 26 is generally of arcuate form. The curvature of the back of the plow 26 is the same as the curvature of the forward portion of element 16. The cross section of the plow is clearly illustrated in FIG. 5 and is that of a truncated equilateral triangle. The center of curvature is contained in the plane including a. median of the triangle, this is the plane upon which FIG. 4 is taken. Therefore one side of the triangle generates a cylindridal surface which is the back surface 32 of the plow. The center portion of the plow is flattened so that it has a place for bolt holes 30 made to receive bolts 24. The upper portion of the bolt holes are counter-sunk and square so that they receive the heads of bolts 24 as is customary with commercial plow bolts. The plow points on each end are initially sharpened by removing metal on the two sides of the triangle which form the forward face of the plow when in use.

In use when the point strikes an obstruction, the backward forces on the point will tend to straighten the arcuate portion 16 and 20. This will tend to make the point go deeper. Iowever, the force on the point of plow 26 will also exert a turning moment about the horizontal portion 12. This will tend to lift the plow from the ground. A combination of these two movements will cause the point of the plow to remain at the same elevation. This is the reason that the flexibility of the horizontal portion 12 and the arcuate portion 16 and 20 must be so nicely correlated. The correlation is achieved by the length of the horizontal portion 12, the radius of the arcuate portion, and the loop 18 which is six inches inside diameter.

The motion as described above, will cause the point of the plow to wear at an angle to the horizontal in the relaxed position. This angle of wear is shown by the dotted line BB in FIG. 7 where line AA represents the major portion of the wear will occur along the bottom as described. However, the triangular shape of the plow is such that even when it wears along the line B-B, the plow still takes to the ground and does not tend to ride out of the furrow.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction, materials, and arrangement within the scope of the invention as defined in the appended claims.

I claim as my invention:

1. In a subsoil shank having a horizontal portion and a downward arcuate portion, with means on the forward portion of the horizontal portion for attaching the shank to a carrying beam so that the shank lies parailel to the direction of draft, and means at the lower end of the arcuate portion for attaching a plow; the improvement comprising: said arcuate portion and rear part of said horizontal portion comprising elements which are more than a single integral part, one of said elements extending from the horizontal portion and flaring smoothly into the arcuate portion which extends downward, a second element extending from the rear of the horizontal portion into a single upward turned helical loop, said helical loop terminating with a tangent portion which lies along and contacts the first mentioned arcuate portion, said two arcuate portions being aligned in the direction of the draft.

2. The invention as defined in claim 1 wherein said elements are joined along the horizontal portion to form a single integral element forward of the point of joinder, and the horizontal portion has a cylindrical bore at the point of joinder to eliminate a high stress point.

3. The invention as defined in claim 1 wherein the means at the lower end of the arcuate portion for attaching a plow includes bolt holes extending through two of said elements, and the addition of a boss on one element extending toward said other element, and said other element having a depression correlative to said boss, said boss proximate said bolt holes, so that relative movement of said elements is restricted.

4. The invention as defined in claim 1 with the addition of a subsoil plow attached to the means at the lower end of the arcuate portion, said plow having the general curvature of the arcuate portion so that it contacts the shank along a substantial portion of its length, said plow having the cross section of a truncated equilateral triangle, said plow having sharpened extremities and a means in the center thereof for attaching said plow to said shank.

References Cited in the file of this patent UNITED STATES PATENTS 406,256 Brinkerhoff July 2, 1889 1,108,600 McCulley et al Aug. 25, 1914 2,259,890 Hippie Oct. 21, 1941 2,689,514 Ferguson Sept. 21, 1954 2,737,870 Cook Mar. 13, 1956 

1. IN A SUBSOIL SHANK HAVING A HORIZONTAL PORTION AND A DOWNWARD ARCUATE PORTION, WITH MEANS ON THE FORWARD PORTION OF THE HORIZONTAL PORTION FOR ATTACHING THE SHANK TO A CARRYING BEAM SO THAT THE SHANK LIES PARALLEL TO THE DIRECTION OF DRAFT, AND MEANS AT THE LOWER END OF THE ARCUATE PORTION FOR ATTACHING A PLOW; THE IMPROVEMENT COMPRISING: SAID ARCUATE PORTION AND REAR PART OF SAID HORIZONTAL PORTION COMPRISING ELEMENTS WHICH ARE MORE THAN A SINGLE INTEGRAL PART, ONE OF SAID ELEMENTS EXTENDING FROM THE HORIZONTAL PORTION AND FLARING SMOOTHLY INTO THE ARCUATE PORTION WHICH EXTENDS DOWNWARD, A SECOND ELEMENT EXTENDING FROM THE REAR OF THE HORIZONTAL PORTION INTO A SINGLE UPWARD TURNED HELICAL LOOP, SAID HELICAL LOOP TERMINATING WITH A TANGENT PORTION WHICH LIES ALONG AND CONTACTS THE FIRST MENTIONED ARCUATE PORTION, SAID TWO ARCUATE PORTIONS BEING ALIGNED IN THE DIRECTION OF THE DRAFT. 